Discussion on the ruling of saying "Ameen" to one who says "May Allah accept it" after the prayer

The student : He insisted that I say "May Allah accept it" or that I say "Ameen," and he repeated it a second and third time. Then my brother Abu Ayyub said, "Say Ameen, there is nothing wrong with it." I said to him, "My brother, this is not from the Sunnah. If you must say something to your brother, say it."
Another student: Ameen to what?
The student : To "May Allah accept it." I said, "If you must say something to your Muslim brother, say 'Peace be upon you.'" My brother Abu Ayyub said, "It is not like that. Why do you speak to him in this manner? You are driving him away. You are such and such." I said to him, "My brother..."
Another student: ...
Another student: May Allah forgive you.
The student : "Ameen." I said to him, "My brother, this is not from the Sunnah, 'May Allah accept it.'" He said, "There is nothing wrong with saying it to him." I said to him, "If I say 'May Allah accept it' to him, I have agreed with him in this religious innovation." I said to him, "Okay, fine, we will ask the shaykh, by the door of . He thinks that I mean, I am asking the shaykh, meaning that our shaykh, what he says is what happens. You do not say anything from your own pocket. You do not say anything according to your own desires. Rather, you bring us the Sunnah of the Beloved - (peace and blessings be upon him) -."

The Shaykh : If Allah wills.
The student : So he took it out on me and got angry, and said to me, "You are unjust." I said, "Peace be upon you," and he left.
Another student: Who told you, "You are unjust"?
The student : Abu Ayyub.
Another student: No, that was an offensive peace...